An EER (Envelope Elimination and Reconstruction) system is adopted in an ordinary power amplifier that supplies an electric power to the radio communication device (see JP-A No. 2006-203456 (Kokai)). In the EER system, an envelope component of an input signal is processed by an envelope detector, and a phase component (hereinafter referred to as “input phase”) of the input signal is processed by a limiter. The limiter shifts the input phase using an AM-PM (Amplitude Modulation-Phase Modulation) conversion method to generate a phase component (hereinafter referred to as “output phase”) of an output signal.
However, in the EER system disclosed in JP-A No. 2006-203456 (Kokai), a degree of AM-PM conversion increases with increasing range (input amplitude range) of amplitude (hereinafter referred to as “input amplitude”) of the input signal. Particularly, in an OFDM (Orthogonal Frequency Division Multiplexing) system, the degree of AM-PM conversion increases because of the wide input amplitude range (about 40 dB). Additionally, an allowable range of the degree of AM-PM conversion is comparatively narrow in the EER system disclosed in JP-A No. 2006-203456 (Kokai). Accordingly, the EER system disclosed in JP-A No. 2006-203456 (kokai) cannot be applied to the OFDM-system radio communication device having the wide input amplitude range.